JP7394617B2 - Air ratio estimation system, air ratio control system, and unburned detection system or misfire detection system - Google Patents

Description

The present invention relates to an air ratio estimation system capable of estimating the air ratio (equivalent ratio) in combustion equipment related to hydrocarbon gas fuel, an air ratio control system using this air ratio estimation system, and an unburned detection system or misfire detection system. Regarding detection systems.

As a method for calculating and controlling the equivalence ratio in each combustion chamber of a gas turbine combustor, the method described in JP-A-7-332609 (Patent Document 1) is known.
The calculation of the fuel-air ratio here is based on three of the various radicals (unstable chemical species) (OH radical, CH radical, C This is done by determining the equivalence ratio from the relative luminance obtained from the flame image based on the relationship between the relative luminance of light emission and the equivalence ratio (reciprocal of the fuel-air ratio) for each of _{the two} radicals. OH radicals have a high emission intensity in the wavelength range of 306 to 320 nm (nanometers), CH radicals have a peak emission intensity around a wavelength of 432 nm, and C ₂ radicals have a peak emission intensity around a wavelength of 517 nm. The emission intensity has a peak at .

Japanese Patent Application Publication No. 7-332609

In calculating the fuel-air ratio above, the equivalence ratio is obtained based on the relative brightness obtained from the flame image for each of OH radicals, CH radicals, and _C2 radicals. Noise impairs the accuracy of the equivalence ratio.
Further, in particular, the relative brightness of OH radicals requires a camera capable of capturing images in the ultraviolet region, and calculation of the equivalence ratio becomes a large-scale task.
Therefore, the main object of the present invention is to provide a more accurate air ratio estimation system that is less susceptible to noise.
Another main object of the present invention is to provide an air ratio estimating system that has a simple configuration and can estimate the air ratio more easily and at lower cost.
Furthermore, another main object of the present invention is to provide an air ratio control system and an unburned detection system or a misfire detection system in which the above-described air ratio estimation system is used.

The invention according to claim 1 is an air ratio estimating system for estimating an air ratio in a combustion facility in which a flame generated by a hydrocarbon gas fuel occurs, wherein the flame is photographed a plurality of times to obtain a plurality of flame images related to visible light. and a computer that receives the plurality of flame images, and the computer includes a visible light camera that acquires CO-O radical radiation of the flame in a predetermined wavelength range within the visible range from the plurality of flame images. CO-O radical cumulative brightness obtained by extracting and accumulating the brightness of CH radicals, and CH obtained by extracting and accumulating the brightness within the visible range of the CH radical radiation of the flame from the plurality of flame images. Based on the radical cumulative brightness, calculate CH/CO-O, which is a ratio between the CO-O radical cumulative brightness and the CH radical cumulative brightness, and extract the air ratio corresponding to the CH/CO-O. It is characterized by:
According to a second aspect of the invention, in the above invention, the computer is capable of referring to a database indicating a correspondence relationship between the CH/CO-O and the air ratio.
The invention according to claim 3 is characterized in that, in the above invention, the visible light camera and the computer exhibit portability.
The invention according to claim 4 is characterized in that, in the above invention, the combustion equipment has an observation window through which the flame can be visually recognized, and the visible light camera is installed in the observation window. It is something.
The invention according to claim 5 is an air ratio control system, comprising: the air ratio estimating system; an air flow rate regulating valve that adjusts the flow rate of combustion air by the opening degree; The computer includes a gas flow rate adjustment valve to be adjusted, and a computer connected to at least one of the air flow rate adjustment valve and the gas flow rate adjustment valve, and the computer is configured to adjust the air ratio estimated by the air ratio estimation system. The present invention is characterized in that at least one of the opening degree of the air flow rate adjustment valve and the opening degree of the gas flow rate adjustment valve is controlled so as to approach a target air ratio setting value.
The invention according to claim 6 is an unburned detection system or a misfire detection system, comprising the above-mentioned air ratio estimation system and a computer, and the computer is configured to detect the air ratio estimated by the air ratio estimation system. This is characterized in that when the ratio falls below the lower limit air ratio setting value or the misfire air ratio setting value, a message to the effect of unburned or misfire is output.
Note that the computer in the invention according to claims 5 and 6 may be the same as the computer in the air ratio estimation system according to claims 1 to 4, or may be different, or may be partially the same. It's okay.

The main effect of the present invention is to provide a more accurate air ratio estimation system that is less susceptible to noise.
Another main effect of the present invention is that an air ratio estimating system is provided that has a simple configuration and can estimate the air ratio more easily and at lower cost.
Furthermore, another main effect of the present invention is that an air ratio control system and an unburnt detection system or a misfire detection system are provided in which the above-described air ratio estimation system is used.

1 is a schematic cross-sectional view of a combustion furnace to which an air ratio estimation system according to the present invention is applied. 3 is a graph showing the distribution of the relative intensity of flame emission in the visible wavelength range in three cases where the equivalence ratio φ (reciprocal of the air ratio) is 1.0, 1.2, and 1.4. 2 is a flowchart related to an operation example (an example of an air ratio estimation method) of the air ratio estimation system of FIG. 1. FIG. This is a graph showing the correspondence between CH/CO-O (INTENCITY (cumulative brightness ratio)) and air ratio, and shows that the flow rate of combustion gas G is 0.4, 0.5, 0.6 (the rated flow rate is 1 is a graph showing the correspondence relationship when the flow rate is 1).

Hereinafter, examples of embodiments according to the present invention, together with modifications thereof, will be described based on appropriate drawings.
Note that this form is not limited to the following examples and modifications.

FIG. 1 is a schematic cross-sectional view of a combustion furnace P (combustion equipment) to which an air ratio estimation system 1 according to the present invention is applied.

The combustion furnace P has a main body C and a burner B.
The main body C is a box made of a heat insulating material. The inside of the main body C is a combustion chamber R.
Burner B is installed on one wall W in main body C. A hole H is provided in the wall W. Burner B is provided so as to cover hole H. Burner B mixes combustion air A and combustion gas G, and blows the mixture into combustion chamber R through hole H.
The flow rate of combustion air A to burner B is adjusted by an air flow rate adjustment valve FA.
The combustion gas G is city gas containing methane as a main component. The flow rate of the combustion gas G to the burner B is adjusted by a gas flow rate adjustment valve FG. The main component of the combustion gas G may be propane, butane, or a combination thereof (hydrocarbon gas fuel containing hydrocarbons as the main component) instead of or together with methane. The components of the combustion gas G may be only methane, only propane, only butane, or only a combination thereof (hydrocarbon gas fuel consisting only of hydrocarbons).

A flow rate control means FC that controls the respective flow rates is connected to the air flow rate adjustment valve FA and the gas flow rate adjustment valve FG.
Note that at least one of the air flow rate adjustment valve FA, the gas flow rate adjustment valve FG, and the flow rate control means FC may be omitted. Further, instead of or together with the flow rate control means FC, an air flow rate control means for controlling the air flow rate adjustment valve FA and a gas flow rate control means for controlling the gas flow rate adjustment valve FG may be provided.

The mixture of combustion air A and combustion gas G is combusted in the combustion chamber R, causing a flame L within the combustion chamber R. The flame L includes a flame root L1 within the flame stabilizing surface L0 and a flame tip L2 outside the flame stabilizing surface L0. Note that the combustion air A and the combustion gas G may be mixed within the combustion chamber R.
A wall W on which the burner B is installed is provided with an observation window O. The observation window O has translucency. The user can visually recognize the flame L in the combustion chamber R through the observation window O. Note that a plurality of observation windows O may be provided. Further, the observation window O may be placed on the opposite side of the burner B, etc., other than the wall W where the burner B is installed.

The air ratio estimation system 1 includes a PC 2 (personal computer) and a camera 4.

The PC 2 includes a PC storage means 10, a PC input means 11, a PC output means 12, a PC communication means 13, and a PC control means 14. The PC side storage means 10 stores various information. The PC side input means 11 can input various information. The PC-side output means 12 is capable of displaying and/or printing various types of information. The PC-side communication means 13 is capable of communicating with equipment external to the PC 2. The PC-side control means 14 controls various means in the PC 2.
The PC 2 is a notebook type that exhibits portability. Note that the PC 2 may be of another type, such as a tablet type, or may be a computer other than a personal computer. Further, the PC 2 may be a stationary computer that is not portable.

The camera 4 includes a lens 20, an image sensor 22, a camera-side storage means 24, a camera-side communication means 26, and a camera-side control means 28. The lens 20 forms an image of light from the outside onto the image sensor 22 . The image sensor 22 images visible light guided by the lens 20. The image sensor 22 has a plurality of pixels, and the brightness values of R (red), G (green), and B (blue) are determined for each pixel through image processing by the camera-side control means 28 as appropriate. Get the image. The camera-side storage means 24 stores various information including images acquired by the image sensor 22. The camera-side communication means 26 is capable of communicating with equipment external to the camera 4. The camera-side control means 28 controls various means in the camera 4.
Camera 4 exhibits portability. Camera 4 is installed at observation window O. The lens 20 and image sensor 22 of the camera 4 are directed toward the flame root L1 and mainly photograph the flame root L1 (see dotted lines D1 and D2 in FIG. 1). The camera 4 is sensitive to visible light and captures images related to visible light (visible light camera). Visible light is light whose wavelength is within the visible range. The visible range here is from 380 nm to 780 nm. Note that the visible range (the wavelength range to which the camera 4 is sensitive) can be changed in various ways, such as a lower limit of 400 nm and an upper limit of 800 nm.
The camera 4 can continuously capture a plurality of images of the flame L, that is, a plurality of flame images 29 at a predetermined number per second. That is, the camera 4 can take a moving image of the flame L.
The camera 4 (camera side communication means 26) is communicably connected to the PC 2 (PC side communication means 13). The PC 2 (PC side storage means 10) can store each image of the flame L received from the camera 4, that is, each flame image 29.
Further, the PC 2 (PC side storage means 10) can control the camera 4 via the PC side communication means 13 and the camera side communication means 26. Note that the camera-side control means 28 may be omitted and the camera 4 may be completely controlled by the PC 2.

Based on various information obtained from the camera 4, the PC 2 estimates the air ratio in the combustion furnace P where the flame L caused by the combustion gas G occurs in the burner B.
PC2 is connected to flow control means FC.
The PC 2 can perform various controls related to the combustion furnace P (burner B) as shown below according to the estimated air ratio.
That is, based on the estimated air ratio, the PC 2 controls at least one of the air flow rate adjustment valve FA and the gas flow rate adjustment valve FG via the flow rate control means FC to adjust the flow rate of the combustion air A and the combustion gas. At least one of the flow rates of G is automatically adjusted. For example, if the estimated air ratio differs (by a certain degree or more) from the target air ratio setting value, which is the value of the air ratio set in advance to be the target, the PC 2 adjusts the air ratio to approach the target air ratio setting value. , adjust at least one of the flow rate of combustion air A and the flow rate of combustion gas G. Note that the flow rate of the combustion air A may be adjusted by adjusting the rotation amount of a motor connected to the air flow rate adjustment valve FA. The same applies to the adjustment of the flow rate of the combustion gas G.
In addition, when the estimated air ratio becomes less than the lower limit air ratio setting value, which is the air ratio value set in advance to be the lower limit when normal combustion is maintained, the PC2 The output means 12 outputs an alarm to the effect that the air ratio has become less than the lower limit air ratio setting value. If the air ratio becomes smaller than a predetermined level, the combustion state in the combustion furnace P will be incomplete (unburned), creating a danger such as the possibility of carbon monoxide generation. Announce the fire. Incidentally, when the flow rate control means FC is provided with an output means, the output means of the flow rate control means FC may issue an alarm.
Similarly, PC2 determines the misfire air ratio set value when the estimated air ratio becomes less than the misfire air ratio set value, which is the air ratio value preset as a possible value when combustion is not maintained. Outputs a warning to the effect that it has become less than the specified value. The PC 2 notifies the user of the misfire by issuing a misfire alarm.

Hereinafter, estimation of the air ratio in the combustion furnace P by the air ratio estimation system 1 will be explained in more detail.
FIG. 2 is a graph showing the distribution of the relative intensity of flame emission at wavelengths in the visible range in three cases where the equivalence ratio φ (reciprocal of the air ratio) is 1.0, 1.2, and 1.4.
Generally, in the decomposition process of hydrocarbons, the following reactions occur within a short time, and various radicals are generated as active and short-lived intermediate chemical species (unstable chemical species). Note that " ^* " indicates an excited state. Further, "hv" indicates the energy of light of frequency ν (h is Planck's constant).
C ₂ +OH→CO+CH ^* ...Formula 1
CH+O ₂ →CO+OH...Formula 2
CO+O ₂ →CO ₂ +hν...Formula 3

At the beginning of the hydrocarbon decomposition process, the C ₂ radical appearing on the left side of Equation 1 is generated. _C2 radicals emit light from electronic excitation. The emission of C ₂ radicals (C ₂ radiation) has three maximum values (band heads) of relative intensity (swan band). The wavelengths related to the band head are 473.7 nm, 516 nm, and 563.6 nm in this order. The maximum value at 516 nm (emission intensity) is larger than the other two maximum values, and increases as the equivalence ratio increases. Therefore, as the equivalence ratio becomes larger (the mixture becomes richer), the flame L (especially the flame root portion L1) approaches green.
Furthermore, CH radicals appearing on the right side of Equation 1 and Equation 2 are generated. Of these, light is emitted from CH ^* (CH radiation). CH radiation has a bandhead at a wavelength of 431.5 nm in the visible range. The CH radiation contributes to the blue color of the flame L (particularly the flame root L1). Note that CH radiation also has a bandhead at a wavelength of 387.2 nm in the ultraviolet region.
Furthermore, along with the reaction of formula 3 as the final stage oxidation reaction, light emission called CO--O radiation is generated. The reaction of Formula 3 is called "CO--O radiation" because not only CO is simply oxidized by oxygen molecules, but also active oxygen atoms are involved. This CO-O radiation has a relatively high relative intensity over a range from 350 nm to 500 nm (continuous spectrum).
These light emission modes are noticeable at the flame root L1, where the decomposition of hydrocarbons is promoted, and are different at the flame tip L2, where the hydrocarbons are not completely decomposed and contains soot. becomes.
Note that the OH radicals appearing in Formulas 1 and 2 have high emission intensity in the ultraviolet region of 306 nm or more and 320 nm or less. Therefore, the camera 4 having sensitivity in the visible range cannot photograph light in this wavelength range.

In this way, the intensity of the bandhead of _C2 radiation increases as the equivalence ratio increases, that is, it decreases as the _air ratio increases. It is conventional practice to estimate the ratio. However, in reality, it is difficult to accurately measure the intensity of the _C2 radiation bandhead because it is affected by other radiation, external light, etc., and it is difficult to accurately estimate the air ratio.
Therefore, in order to achieve more accurate estimation of the air ratio, the applicant focused on CO--O radiation emitted in the blue region (FIG. 2).
However, since CO-O radiation has a continuous spectrum and there is a bandhead of CH radiation within its wavelength range, it is better to estimate the air ratio by measuring the intensity of CO-O radiation. It is more accurate to estimate the air ratio using an element that takes into account the intensity of the CH radiation and the intensity of the CH radiation.
Therefore, the applicant discovered that the air ratio can be estimated based on the ratio of the intensity of CO--O radiation to the intensity of CH radiation (CH/CO--O).

FIG. 3 is a flowchart relating to an example of the operation of the air ratio estimation system 1 (an example of an air ratio estimation method).
First, each value of RGB brightness (RGB value) corresponding to the wavelength of the emitted light of each radical is determined by at least one of analysis of multiple samples, imaging simulation, and characteristic analysis of the camera 4 (in particular, the imaging device 22). Based on this, the PC 2 calculates this in advance (step S1).
Here, RGB values corresponding to light with a wavelength of 431.5 nm are determined as CH radiation, and RGB values corresponding to light in a wavelength range of 380 nm to 390 nm are determined as CO-O radiation. Note that when the RGB values of the CH radiation are known, the PC 2 may subtract the brightness corresponding to the CO-O radiation in the wavelength range from 380 nm to 390 nm from the overall brightness in the wavelength range.
It is preferable that the wavelength range of CO--O radiation is set to 380 nm or more and 390 nm or less for the following three reasons. First, the wavelength range according to the setting is far from the bandhead of CH radiation, and the influence of CH radiation is reduced. Second, the wavelength range according to the setting is far from the bandhead of C ₂ radiation, reducing the influence of C ₂ radiation. Thirdly, there is less blue external light (on the short wavelength side of the visible range) than green external light (on the intermediate visible range), and the influence of the external light is reduced. Note that the wavelength range set as corresponding to CO-O radiation is not limited to the above-mentioned wavelength range of 380 nm or more and 390 nm or less, but includes, for example, the 431.5 nm bandhead of CH radiation and the 473.7 nm bandhead of _C2 radiation. The distance between the band head and the band head may be 440 nm or more and 460 nm or less, or at least one of the upper and lower limits may be changed to 385 nm or more and 410 nm or less, or 380 nm or more and 400 nm or less, and 440 nm or more and 460 nm or less. Multiple settings may be made.
This step S1 may be omitted when estimating the air ratio of the combustion furnace P if it has already been performed by prior data analysis.

Next, the PC 2 instructs the camera 4 to take a flame image 29 (one still image) for initial analysis, and acquires and reads the flame image 29 from the camera 4 (step S2). The flame image 29 for initial analysis is stored in the PC side storage means 10.
Subsequently, the PC 2 sets a range (analysis range) for performing image analysis related to air ratio estimation from the read flame image 29 for initial analysis (step S3). The PC 2 determines, in the flame image 29 for initial analysis, a region that covers the center of the flame root L1 by at least one of image analysis and range designation by the operator via the PC-side input means 11. Set the analysis range.
In addition, the PC 2 scans the part of the flame image 29 for initial analysis within the analysis range set in step S3 to determine whether or not the RGB values of each radical radiation calculated in step S1 exist. Extraction of radical radiation and analysis of brightness values are performed (step S4).
Note that at least one of steps S3 and S4 may be omitted.

Then, the PC 2 instructs the camera 4 to continuously acquire flame images 29 within a predetermined period of time (step S5). The camera 4 continuously acquires flame images 29 within a predetermined period of time, and transmits a group of flame images 29 to the PC 2 one after another or all at once. The camera 4 captures a group of flame images 29 for 5 seconds at a shooting speed that captures a predetermined number of images per second. Note that the predetermined number of sheets may be adjusted depending on the state of the flame L and the like. Further, the total imaging time may be less than 5 seconds or may be more than 5 seconds.
Furthermore, the PC 2 calculates each cumulative brightness of each radical radiation within the analysis range of each flame image 29 (step S6). Here, the PC 2 first analyzes the CH radical radiation, the CO-O radical, and the The total luminance of radiation (cumulative luminance per second of CH radical emission, cumulative luminance per second of CO-O radical emission) is integrated. Next, PC2 calculates the cumulative brightness (CH) of CH radical radiation per unit time by averaging the cumulative brightness for five CH radical emission seconds, and calculates the cumulative brightness (CH) of CH radical radiation for a unit time by averaging the cumulative brightness for five CO-O radical radiation seconds. The cumulative brightness of CO-O radical radiation (CO-O) is calculated.
Note that at least one of steps S1 to S4 may be performed based on at least one of continuously acquired flame images 29 instead of the flame image 29 for initial analysis.

Then, the PC 2 divides CH (cumulative brightness) by CO-O (cumulative brightness) to calculate CH/CO-O (step S7).
Next, the PC 2 extracts the air ratio corresponding to CH/CO-O, and outputs the estimated air ratio by the PC side output means 12 (step S8). A database 30 showing the correspondence between CH/CO-O and air ratio is stored in the PC side storage means 10. The PC 2 refers to the database 30 and obtains the air ratio corresponding to CH/CO-O.
Note that the PC 2 calculates partial CH/CO-O for each flame image 29 or multiple flame images 29, and calculates CH/CO-O by accumulating the partial CH/CO-O. Also good.

FIG. 4 is a graph showing the correspondence between CH/CO-O (INTENCITY (cumulative brightness ratio)) and air ratio, and shows that the flow rate of combustion gas G (flow rate when the rated flow rate is 1) is It is a graph showing the correspondence relationship in the case of 0.4, 0.5, and 0.6. This correspondence relationship is obtained in advance by precise measurement of CH/CO-O with a determined air ratio in an experimental furnace or the like for each flow rate of the combustion gas G.
When estimating the air ratio using the air ratio estimation system 1 in the combustion furnace P to be estimated, a combustion gas flow meter that measures the flow rate of the combustion gas G is installed as an estimation method, and the combustion gas flow meter measures the flow rate of the combustion gas G. One example is one in which CH/CO-O is calculated while the flow rate of gas G is ascertained. In this case, for example, if the flow rate ratio of combustion gas G is 0.4 and CH/CO-O is 0.9, as indicated by "○" (circle mark) in FIG. 4, then the air ratio is 1. Estimated to be 5.

Further, when the target air ratio setting value is set to 1.2 and the estimated air ratio is 1.0, the PC 2 controls the air flow rate adjustment valve so that the air ratio approaches 1.2. Increase the opening degree of FA to increase the flow rate of combustion air A, or instead of increasing the flow rate of combustion air A, or together with the increase in the flow rate of combustion air A, increase the opening degree of the gas flow rate regulating valve FG. to reduce the flow rate of combustion gas G (air ratio control system, air ratio adjustment system).
Furthermore, if the lower limit air ratio setting value is set to 1.05, and the estimated air ratio is less than 1.05, the PC 2 outputs a message indicating that there is no combustion through the PC side output means 12 (unburned). burn detection system, unburnt alarm system). Note that when the estimated air ratio falls below the lower limit air ratio setting value, the PC 2 may perform control similar to the control that approaches the target air ratio setting value, and in such control, the degree of change in flow rate is may be made larger (or smaller) than the control that approaches the target air ratio set value.
Further, if the misfire air ratio setting value is set to 0.8, for example, and the estimated air ratio is less than 0.8, the PC 2 outputs a misfire notification to the PC side output means 12 (misfire detection). system, misfire alarm system). Note that the PC 2 may stop combustion in the burner B (supply of the combustion gas G) when the estimated air ratio falls below the misfire air ratio setting value.

Such an air ratio estimation system 1 has the following effects.
That is, the air ratio estimation system 1 estimates the air ratio in the combustion furnace P where the flame L is generated by the combustion gas G (city gas), and acquires a plurality of flame images 29 by photographing the flame L multiple times. and a PC 2 that receives a plurality of flame images 29, and the PC 2 extracts and accumulates the luminance within the visible range of the CO-O radical radiation of the flame L from the plurality of flame images 29. Based on the CO-O radical cumulative brightness CO-O obtained by CH/CO-O, which is the ratio between the CO-O radical cumulative brightness CO-O and the CH radical cumulative brightness CH, is calculated, and the air ratio corresponding to CH/CO-O is extracted.
Therefore, the air ratio estimation system 1 estimates the air ratio based on the ratio between the CO-O radical cumulative brightness CO-O and the CH radical cumulative brightness CH, and therefore estimates the air ratio based on the brightness of CH radical radiation. It is less affected by noise and has higher accuracy than in the conventional case. In addition, the air ratio estimation system 1 can estimate the air ratio using the camera 4 that is sensitive to visible light, and there is no need to use a camera that is sensitive to ultraviolet rays as in the case of measuring OH radical radiation. In addition, the air ratio can be estimated more easily and at lower cost.

Further, the PC 2 can refer to a database 30 that shows the correspondence between CH/CO-O and air ratio. Therefore, in the air ratio estimation system 1, by preparing the database 30 in advance, the air ratio corresponding to CH/CO-O can be immediately obtained.
Furthermore, the camera 4 and the PC 2 exhibit portability. Therefore, the air ratio estimation system 1 exhibits portability and is capable of estimating air ratios in combustion furnaces P and the like located in various locations.
In addition, the combustion furnace P has an observation window O through which the flame L can be visually recognized, and the camera 4 is installed in the observation window O. Therefore, the air ratio estimation system 1 can easily estimate the air ratio using the observation window O of the combustion furnace P.

Further, the above-described air ratio control system has the following effects.
That is, the air ratio control system includes an air ratio estimation system 1, an air flow rate adjustment valve FA that adjusts the flow rate of combustion air A by the opening degree, and a gas flow rate adjustment valve that adjusts the flow rate of the combustion gas G by the opening degree. FG, and a PC2 connected to at least one of an air flow rate adjustment valve FA and a gas flow rate adjustment valve GA, and the PC2 is configured to adjust the air ratio estimated by the air ratio estimation system 1 to the target air ratio setting value. At least one of the opening degree of the air flow rate adjustment valve FA and the opening degree of the gas flow rate adjustment valve FG is controlled so that the opening degree of the air flow rate adjustment valve FA and the gas flow rate adjustment valve FG approach each other.
Therefore, the air ratio control system can be constructed more easily and at lower cost while being less susceptible to noise and capable of more accurate control.

Furthermore, the above-described unburned detection system or misfire detection system has the following effects.
That is, the unburned detection system or the misfire detection system includes an air ratio estimation system 1 and a PC 2, and the PC 2 is configured to determine whether the air ratio estimated by the air ratio control system 1 is the lower limit air ratio setting value or the misfire air ratio. If the ratio is below the set value, a message indicating no combustion or misfire is output.
Therefore, an unburned detection system or a misfire detection system can be constructed more easily and at a lower cost while being less susceptible to noise and capable of more accurate detection.

Incidentally, the present invention further has the following modifications as appropriate.
The combustion equipment may be a gas turbine, an industrial furnace, a drying furnace, a boiler, etc.
Further, the air ratio may be adjusted not by the PC 2 but by manual operation of at least one of the air flow rate adjustment valve FA and the gas flow rate adjustment valve GA.

1... Air ratio estimation system, 2... PC (computer), 4... Camera, 29... Flame image, 30... Database, A... Combustion air, FA... Air flow rate adjustment valve, FG... Gas flow rate adjustment valve, G... Combustion gas (hydrocarbon gas fuel), L... Flame, O... Observation window, P... Combustion furnace (combustion equipment).

Claims (6)

An air ratio estimation system for estimating an air ratio in combustion equipment in which a flame generated by hydrocarbon gas fuel occurs,
a visible light camera that photographs the flame multiple times to obtain multiple flame images related to visible light ;
a computer that receives the plurality of flame images;
It is equipped with
The computer extracts and accumulates the luminance in a predetermined wavelength range within the visible range of the CO-O radical radiation of the flame from the plurality of flame images, and the plurality of CO-O radical cumulative luminances. The ratio of the CO-O radical cumulative brightness to the CH radical cumulative brightness, based on the CH radical cumulative brightness obtained by extracting and accumulating the brightness in the visible range of the CH radical radiation of the flame from the flame image. An air ratio estimation system characterized in that the air ratio estimation system calculates CH/CO-O, and extracts the air ratio corresponding to the CH/CO-O. 2. The air ratio estimating system according to claim 1, wherein the computer can refer to a database showing a correspondence relationship between the CH/CO-O and the air ratio. The air ratio estimation system according to claim 1 or 2, wherein the visible light camera and the computer are portable. The combustion equipment has an observation window through which the flame can be viewed,
The air ratio estimation system according to any one of claims 1 to 3, wherein the visible light camera is installed in the observation window. The air ratio estimation system according to any one of claims 1 to 4,
an air flow rate adjustment valve that adjusts the flow rate of combustion air by opening;
a gas flow rate adjustment valve that adjusts the flow rate of combustion gas by the opening degree;
a computer connected to at least one of the air flow rate adjustment valve and the gas flow rate adjustment valve;
It is equipped with
The computer controls at least one of the opening degree of the air flow rate adjustment valve and the opening degree of the gas flow rate adjustment valve so that the air ratio estimated by the air ratio estimation system approaches a target air ratio setting value. An air ratio control system featuring: The air ratio estimation system according to any one of claims 1 to 4,
computer and
It is equipped with
The computer outputs an indication of unburned or misfired when the air ratio estimated by the air ratio estimation system is lower than a lower limit air ratio setting value or a misfire air ratio setting value. system or misfire detection system.

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